Laptop power fan on but no display on screen

Hello,


i have a hp laptop and when i switch it on there is a power light on and the fan cmes on however the symbol that i think represents the harddrive is not flashing. i brought it to techguys and the guy did the take the battery out and hold the power button for thirty seconds but this has not solved the problem. is there any other ideas for me to try?? i would be greatful of any help! :)